An unusual muscle anomaly is reported which simulated a soft-tissue neoplasm in the hand. It was considered to be a duplication of the hypothenar muscles. No identical case could be found in the literature. The function and appearance of the hand are reported to be excellent almost three years after excision of the anomalous three-headed muscle and the major portion of a very large palmaris brevis muscle. Section of the proximal pulley of the distal fibrous flexor tendon sheath of the little finger, because of a trigger finger, was also performed.